The significant utility of waterbeds by bed patients has been recognized for a long, long time. U.S. Pat. No. 254,265 issued in 1882 to Edwin James Bone suggested a waterbed structure for bed patients to reduce the possibility of bed sores.
Bed patients often require a reclining back, particularly during waking hours. If bulky pillows or other supplemental supports are used, the value of the fluid suspension is lost. One of the objects of the present invention is to provide a simple reclining back waterbed that provides fluid support not only when the back is horizontal, but also when it is tilted.
The water contained in a waterbed mattress or bag may be entirely unstressed, or it may be somewhat pressurized. This depends upon the relationship of the plastic containing the water, the degree of fill, the nature of the peripheral support for the bag and the load or weight of the person occupying the bed. For ordinary domestic use, it was suggested by early waterbed pioneers that complete flotation was most desirable for restful sleep. Flotation was made possible by providing a rigid peripheral support and a degree of fill short of that sufficient to stress the top plastic layer. It is now recognized that complete flotation is disturbing. A substantial firmness is required even for domestic use. For hospital use, however, the degree of firmness becomes quite critical to patient comfort. It is believed that maximum comfort and the minimum possibility of bed sores is achieved if the fluid pressure of the body of the bed occupant equates to or closely relates to the fluid pressure of the mattress itself. Accordingly, it is another object of this invention to provide a tilting hospital bed that provides control of fluid pressure throughout the operative area of the bed.